Apparatus for casting dental plates.



F. W. TRACY. APPARATUS FOR CASTING DENTALPLATES. APPLIQATION FILED MAY9, 1908 "926,037, Patented June z, 1909 metrically opposite opening, a,the flask is compressed air-pipe.

Unire srraemrarrznr crimen.

FRANK. W. TRACY, OF CHICAGO, ILLINOIS, ASHIGNOR Ol." UNll-IIALI" Tf)fI'IAItLES MCKINLEY,

. Ul" CHICAGO, ILLINOIS.

APPARATUS FOR CASTING- DENTAL PLATES.

Specification of Letters Patent.

Patented. June 22, 1909.

Application filed May 9, 1908. Serial No. 431,886. l

'.o all 'whom t 'may concern:

Be it known that l, Fnxxn lV. Timor, a citizen of the United States, anda resident of' Chicago, in the county of Cook and State of Illinois,have invented certain new and useful Improvements in Apparatus forCastingDental Plates, of which the following is a clear, full, and exactdescription.

My invention relates to means for casting' dental Work and particularlyplates for false teeth. Heretofore dentists have hadconsiderableldifiiculty in casting this comparatively large Work, owingto the diflieulty in getting the air out of the mold, and in getting themetal to flow into all parts of the same, and particularly owing to thepeculiar plastic condition of aluminum, which is the metal usuallyemployed for this purpose.

The object of my invention is to overcome these difficulties and toproduce a smooth perfect casting` economically and quickly`substantially as hereinafter fully described and as particularlypoint-ed out in the claims.

In the drawings:-Figure l is a perspective'vieW of my improved flask.Fig'. 2 is a transverse section of the same in a horizontal position,showing the crifcible former in place. Fig'. 3, is a similar view of thesame, set vertically on edge, and showing;- the manner of melting themetal in the crucible. Fig. 4 is a side elevation of the flask, taken atright angles to that shown in F ig'. 3, and the siuerimposed means forpneumatically forcing the metal into the mold. shown in vertical centralsection. Fig. 5 is a detail View of the discharge end of the Theprincipal part `of my invention comprises a metal flask A, which is,preferably, cylindrical in shape and has a closed bottom and an opentop, substantially as shown in the drawings. The inner diameter of thisflask is sufficient to accommodate a plate for false teeth, and aty oneside it is provided with an opening a, whose edges, Z2, are flangedoutward a short distance, and diaprovided with a circular boss d. Thisflask consists of two parts A and A whose. meeting edgesare in a planeparallel with the plane of its top edges, that intersect the axes ofopening' (I, and boss d, and these two parts are secured together by ametal ring c that is slipped over the flanged edges Z) of opening a, andb f an annular plate e, which is placed around boss d and, together withsaid boss, forms a base for the support of the flask when it is set ,onits'side with. openinga. uppermost. The flask is thus made 111 twosections to facilitate the removal of the casting, although it can bemade in one piece if desired.

In use, the investment material (or composition in which themold ismade) isreduced to a plastic state and placed in the flask when thelatter is in a horizontal position, substantially as shown in Fig. 2 ofthtl drawings. The flask is usually filled from one-third to one-halffull, and then the wax pattern B of the plate to be cast is insertedtherein, with the bend or portion of the plate adapted to cover thegums, near the opening a. The remainder of the flask is then filled,after which a Crucible former C is inserted in openinga, until thecircular flange j thereof bears against the outer' edges of flange 11.This former is, preferably, provided with an integral finger-grasp l)extendimc` outward from the flanged end thereof in alinement with itsaxis, whose outer cud terminates iu a knob having milled edges,substantially as shown. The former, (l, is, preferably, of the shape ofthe small cud of an egg. and its truncated end is provided with a shortextension (1 which, when the former is pushed home, substantially aslshown iu Fig. 2, comes in contact: with the bend of the plate-pattern-If this former should not. reach the bend of said pattern a fter theformer is removed, a sprue is made b v any suitable implement which willconnect the crucible with said pattern. l The flask is then subjected toa sufficientdegree of heat. to harden or fix the m'old and to melt thewax, but before this is done, however, l make a small opening or vent linto the exposed surfaces of the plastic investment material, by meansof a Wire E, or other suitable device, which extends to and comes incontact with the broad side of the plate, substantially as shown in Fig.3. If desired, I can make other openings or vents IP, substantially asshown in Fig. 8 of the drawings. llVhen the wax is thus melted it runsout of these vents. After the mold is fixed the base of the flask isseated in a suitable depression or seat in eed G, which corresponds tothe contours thereof, und then the mouth of the opening a is closed bymeans of a suitable presser-'foot H. The lower end preferably, greaterupper portion, and

in diameter .than the between its outer circumference and the centralportion thereof the under engaging surface is recessed and lilled withasbestos /t or other suitable noncombnstible packing, which is retainedin place by a suitableannular-plate The diameter of the solid centralportion of the umlerside'otI the presser-foot corresponds to or isslightly less than the circui'nference of opening, c, of the I'iask,into which it is adapted to enter slightly so as to make the asbestospacking when. the presser-foot is moved downward to the limit of itslower movement` bear tightly upon the upper edges oll flange n, and itsreinforcing band c and make an airtight joint. rlihis presserl'oot isprovided with a suitable central bore, and a pipe or tube, l, titssnugly within and extends through said bore sulliciently tight toprevent the esi-ape of air around its sides. l`he bore of pipe lterminates near the lower end of the saine, but compressed air isdisrharged therefrom by means of a series of orifices which extend in anoutwardly invlined direction through thelower end of the said pipe atpoints equal distances apart. This arrangement. is adopted` in order tothrow the air discharged from pipe Vl in a radial direction against" thesides of the rrmfible. 'lhis.spreading of the air is facilitated by acircular deflector li which is, preferably, of the same diameter as thepipe, and is secured integrally or otherwise to the central portion ot'the pipe l', substantially as shown in Fig. 5 of the drawings. 'l`heobject` in thus spreading the compressed air as it enters the Crucibleis to press the molten metal in the crucible downward equally on allsides, and force the metal into the mold. 'l`l1e metal, whic'h it ispreferred to use for the casting of the plates `lor false-teeth, isaluminum, and when aluminum is melted, it does not flow like othermolten metals but is more the consistency of lard, and has to bepneumatically forced into the mold, before it will till all of thecavities made by the pattern. rllhe use of compressed air or other gasis, therefore, a necessity, but. if the compressed air was dischargedinto the crucible in a lsolid current of this presser-foot is,

in alinement with the axis of the pipe l, yit would bore a hole throughthe molten aluminum, whereas by spreading it the pressure of the air isditfused so'as. tobe equal all over the surface of the molten body ofthe metal and it is forced into the mold in av .satisfactory andefficient manner.

l. A AliaskV consistingr of upper and lower portions the upper face ofone of which is cut away, an opening in one side of said flask, a bosson the opposite side of said flask, and rings surrounding said openingand boss, in combination with a.- Crucible former removably inserted insaid opening and a vent formed in the open side of said mold atsubstantially right angles to the axis of said Crucible.

2. A dental mold having the crucible and sprue made in the inclosed edgethereof, a vent in the uncovered top of the same and means which closethe mouth ot' and discharge air radially into the crueible to force themetal into the mold.

3. dental mold havinn a. erucible therein and sprue extemling axiziilytherefrom into the cavity of the mold, in combination with means adaptedto close the mouth of the crucible and flischarge air under pressureradially into the same.

4. A flask the top of which is always open, and which has an opening-inthe side thereof, in combination with a e'rucible former adapted to beremovably inserted therein and means for closing and discharging airunder pressure radially into saidcrucible.

5, A flask the top of which is always open, and which has an opening inthe side thereof, in combination with a Crucible former adapted to beremovabl'?7 inserted in said opening, ay suitable vent -ormed in themold substantially at right angles to the axis of said crucible, andmeans for closing and discharging air under pressure radially into saidcrueible.

ln testimony whereof t have hereunto set my hand and seal this 2nd dayof May, a. D., i908.

FRANK W. TRACY.

Witnesses 2 Guantes McKinney, FRANK l). 'l`iioivrAsoN.

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